Cleaning oil laden metal waste to recover the metal and reclaim the oil

ABSTRACT

Oil laden metal waste such as turnings, chips and the like are cleaned to remove oil and other impurities from the metal waste enabling recovery of the metal and reclaiming of the oil. The cleaning is achieved through counterflow of a detergent solution in a wash bath, removing the cleaned metal waste from the bath and separating a substantial quantity of the remaining moisture therefrom, and removing the detergent solution from the wash bath and running it through a rehabilitation circuit where it is subjected to centrifugal force to separate sludge and oil from the solution. Then concentrated make up detergent solution is added, the make up and restored detergent solution heated and returned from the rehabilitation circuit to the wash bath.

United States Patent 1191 Keogh, Jr.

[54] CLEANING OIL LADEN METAL WASTE TO RECOVER THE METAL AND RECLAIM THE OIL James R. Keogh, Jr., Philadelphia, Pa.

FMC Corporation, San Jose, Calif. Filed: Aug. 4, 1971 Appl. No.: 169,117

Related U.S. Application Data Division of Ser. No. 53,261, July 8, 1970, Pat. No. 3,639,172, which is a continuation-in-part of Ser. No. 693,298, Dec. 26, 1967, Pat. NO. 3,544,369.

[75] Inventor:

Assignee:

U.S. C1 ..l34/25 R, 134/10, 134/40 Int. Cl. ..B08b 7/04 Field of Search ..134/2, 10, 25 R,

[56] References Cited UNITED STATES PATENTS F HOT ETERGENT May 22, 1973 3,163,929 1/1965 Goodstein ..134/2 FOREIGN PATENTS OR APPLICATIONS 808,901 2/1955 Great Britain ..134/1o 967,010 3/1963 Great Britain Primary Examiner-Joseph Scovronek Assistant Examiner-Stephen B. Davis Attorneyl-1arold J. Birch ABSTRACT Oil laden metal waste such as turnings, chips and the like are cleaned to remove oil and other impurities from the metal waste enabling recovery of the metal and reclaiming of the oil. The cleaning is achieved through counter-flow of a detergent solution in a wash bath, removing the cleaned metal waste from the bath and separating a substantial quantity of the remaining moisture therefrom, and removing the detergent solution from the wash bath and running it through a rehabilitation circuit where it is subjected to centrifugal force to separate sludge and oil from the solution. Then concentrated make up detergent solution is added, the make up and restored detergent solution heated and returned from the rehabilitation circuit to the wash bath.

DETERGENT SOLUTQN STEAM CLEAN METAL PROQLLC U ,9

OIL

Patented May 22, 1913 3,734,776

H01 DETERGENT SOLUT HG. l

CLEANING OIL LADEN METAL WASTE TO RECOVER THE METAL AND RECLAIM THE OIL RELATED APPLICATIONS This is a division of application Ser. No. 53,261, filed July 8, 1970 now U.S. Pat. No. 3,639,172 dated Feb. 1, 1972 which was a continuation-in-part of co-pending application Ser. No. 693,298, filed Dec. 26, 1967 now US. Pat. No. 3,544,369 dated Dec. 1, 1970.

BACKGROUND OF THE INVENTION This invention relates to the art of cleaning metal waste such as metal chips, turnings and the like, and reclaiming oil from such waste. More particularly, the invention is directed to washing such metal waste in a detergent solution to remove the oil and other impurities from the metal waste, reclaiming the oil from the detergent solution and separating sludge picked up by the detergent solution to restore the cleaning capability of the solution to be reused while the cleaned metal waste has excess moisture separated therefrom to provide a commercially acceptable metal product of sufficiently low moisture and oil content such that it may be fed direct to melting furnaces or compressed into briquettes suitable for use in metalurgical reclaiming processes.

Manufacturing industries create vaste quantities of metal waste in their day to day operations, such waste being in the form of chips, turnings, borings and the like. Not only is the metal constituent of this so called waste of recoverable value but also the lubricating oils coating the metal particles or pieces consequent from the manner in which the metal waste is produced are of value to be' reclaimed. In addition to the desired components of the metal and oil, impurities of the type normally attendant operation of industrial facilities are mixed with the metal waste. In handling industrial waste of this nature, it is desirable to be able to compress the metal constituent of the waste into briquettes or directly feed the metal to a melting furnace. In order to accomplish this, it has been found essential that a high percentage of the oil content of the waste be removed preferably to leave the metal constituent at a level of less than approximately 2 percent by weight with respect to the residual oil and moisture content on the recovered metal constituent of the waste.

Prior art proposals have not'provided the capability of recovering both the metal and the oil from metal waste on an economically profitable basis where the metal constituent in the resulting product has sufficiently low moisture and oil content to' enable direct feeding to melting furnaces or compression into briquettes which will possess the desired compressive strength for handling and subsequent use in metalurgical reclaiming processes. Many prior art reclaiming operations for metal waste are directed solely to reclaim- I ing either the metal constituent or the oil constituent and do not provide a combined operation from which overall profitable operation is possible. Other prior art attempts to remove moisture, oil and other impurities from metal chips and the like have been unsuccessful in producing an end product with sufficiently low moisture and oil content that the waste can be formed into briquettes of the high compressive strength of around 10,000 lbs. per square inch deemed necessary for practical handling and use in metalurgical reclaiming processes. Other attempts in the prior art to provide commercially useable end products from metal waste have been so complicated as to substantially increase both the required capital investment and the operating and maintenance expenses in carrying out the process.

SUMMARY OF INVENTION This invention encompasses automatic and continuous cleaning and drying of metal waste such as metal chips, turnings and the like together with the reclamation of oil from such waste. The oil characteristicly associated with the metal component of the waste and other impurities is that used both for cooling and lubrication incident production of the metal chips and tumings. The oil may be of various forms including oils and emulsions and varieties commonly used in metal boring, cutting and like operations.

The invention broadly contemplates crushing the metal waste to achieve a reasonably consistent size of metal particles for handling in the cleaning operation. The waste is washed with a detergent solution of sufficient strength to dissolve the oil carried by the waste thereafter the waste is removed from the wash bath and a substantial quantity of the remaining moisture separated therefrom. The detergent solution is removed from the wash bath after it is exposed to the metal waste and this solution, carrying sludge and oil therewith, passed through a rehabilitation circuit to restore the cleaning capability of the solution before returning the solution to the wash bath for reuse.

The washing is accomplished by providing a flow of detergent solution in a first direction while agitating and removing the metal waste through the flowing detergent solution in a generally opposite direction giving a counterfiow of waste and solution. In the rehabilitation circuit, the detergent solution carrying the sludge and oil therewith is subjected to centrifugal force such that the sludge is separated from the solution and then the oil is separated from the solution. Thereafter, the restored detergent solution has concentrated make up added thereto, is heated, and the make up and restored detergent solution returned from the rehabilitation circuit to the wash bath.

It is a principal object of this invention to overcome the aforementioned problems in the prior art by providing a new and novel cleaning approach for metal waste such as chips, turnings and the like to enable recovering the metal constituent in a form useable in metalurgical processes and to reclaim the oil carried by such waste.

It is another important object of this invention to provide combined recovery of metal and reclamation of oil in a metal waste cleaning operation accomplished in a simple and relatively inexpensive manner requiring minimum capital investment with low operating and maintenance expenses.

A further object of the invention to achieve metal waste cleaning wherein the metal component is recovered at a sufficiently low moisture and oil content as to permit direct feeding of the metal to a melting furnace or allow the metal to be formed into commercially acceptable briquettes.

It is also an object of this invention to provide waste cleaning wherein the optimum amount of oil is recovered from the washing detergent solution in a relatively simple and inexpensive manner while the solution is passing through a rehabilitation circuit to restore its cleaning capability and enable its repeated use in the metal waste washing.

It is also an object of this invention to achieve metal waste cleaning employing a detergent solution of strength sufficient to dissolve the oil carried by the metal waste and thereafter upon the application of centrifugal force to the detergent solution, carrying oil and sludge, obtain rapid separation of the sludge and oil independently of each other leaving the detergent solution in a restored condition to be returned from the re habilitation circuit to the wash bath.

Other objects and advantages, particularly with respect to more specific features, of this invention will become apparent from the following description taken in connection with the accompanying drawing wherein the illustrated embodiment of this invention is set forth by way of illustration and example.

BRIEF DESCRIPTION OF THE DRAWING FIG. 1 is a diagrammatic view with certain components in section, showing the overall interrelationship between components of a metal waste cleaning system in accordance with this invention.

FIG. 2 is a sectional view of each of the metal waste washers taken on lines 2 2 of FIG. 1.

DETAILED DESCRIPTION In the previously filed application Ser. No. 693,298 filed Dec. 26, 1967, as to which this application is a continuation in part, there is contained certain specific description of process steps and apparatus developed for the cleaning of metal wastes by washing in a detergent solution and then restoring the cleaning capability of the solution for its repeated use in the washing operation by removing sludge and oil from the spent detergent solution. This prior parent application described and explained in some detail the types of detergents deemed appropriate for making up the detergent solution. It was there recognized that the particular detergent used in the waste cleaning operation may vary widely dependent on the type of chip, cutting or form of metal waste; the particular metal constituent such as aluminum, cast iron, brass, etc,; the type of soil or other impurities contained in the particular metal waste being cleaned; the type of oil incorporated in the metal waste to be cleaned; etc. Actually, any number of a wide variety of dry or liquid detergents may be suitable for use with the system disclosed. The above mentioned aspects, fully discussed in the above identified parent application, are not repeated herein but reference is made to their being discussed in the prior copending application and they are to be considered incorporated in this application as if repeated in their entirety. Hereinafter, more specific description of the particular embodiment shown in the drawing accompanying this continuation in part application will be set forth along with discussion pointing out the particular advantages deemed to reside in this embodiment of the invention.

FIG. I shows the overall layout, in diagrammatic form, of a metal waste cleaning system showing the flow and treatment of the constituents handled in the process of cleaning metal waste.

The system shown in the embodiment of FIG. 1 commences with the provision of a feeder having a hopper 12 in which the metal waste which to be cleaned and have the oil and metal constituents separated for reuse is retained. The feeder 10 may take anyone of a variety of conventional forms with a screw type feeder having a feed screw 14 driven by a motor 16 being diagrammatically illustrated to control feed of the metal waste from hopper 12 and discharge it from the feeder outlet 18 into the metal waste washer 20.

The metal waste washer 20 specifically illustrated in the embodiment of FIG. 1 is made up of two similar wash sections connected in series. However, it is to be understood that depending upon the conditions of the metal waste, detergent solution, desired retention time in the detergent solution for the metal waste and other variables involved in carrying out the waste washing operation, the washer 20 may be constructed of a single section or even constructed of a plurality of sections greater than two.

Where adequate exposure time of the metal waste to the detergent solution to obtain the desired waste cleaning cannot be achieved by a single washer section, it is beneficial to employ a plurality of sections in series like the two illustrated on FIG. 1. The alternative of simply increasing the length of one section of the washer has the drawback that such would entail the undesirable addition of screw supporting hanger bearings intermediate the ends of the feed screw with such bearings being exposed to the abrasive material of the metal waste. Thus, in washing particularly dirty or oily waste, increase in the washing time by using a multiple section washer such as illustrated is desirable.

As heretofore mentioned, the sections of the metal waste washer 20 are similar and accordingly, description of only one section should suffice for understanding of the contemplated construction for washer 20. The washer has a longitudinally extending and upwardly inclined tank 22 with a spiral ribbon conveyor 24 operatively mounted longitudinally within the tank to be driven by motor 26 in propelling the metal waste through the flow of detergent solution and agitating such waste so that maximum exposure of the surfaces of the metal waste particles to the cleaning by the detergent solution will occur.

Referring to FIG. 2, it will be seen that the tank 22 is generally U-shaped in cross section having a semicylindrical bottom conforming generally to the exterior of spiral ribbon conveyor 24. The tack 22 retains a wash bath of the detergent solution into which the metal waste is discharged from outlet 18 of feeder 10. The lower rear end of the tank 22 provides a wier over which the spent detergent solution flows into a trough 28 from which such solution is led to the rehabilitation circuit wherein the cleaning capability of the solution is restored as will be described.

Where a multiple section washer. 20 such as illustrated in FIG. 1 is to be used the sections are mounted in series. As so disposed, the spiral ribbon conveyor 24 in the first section is driven by motor 26 to propel and agitate the metal waste within the wash bath of detergent solution to be moved upwardly along the inclined bottom of the tank 22 and finally discharged at the upper end of the tank through outlet 30. This outlet is positioned to overlie the lower end of the next succeeding washer section so that the metal waste is discharged into such next section and there exposed to a second portion of the tank bath.

In this next section, a similarly formed tank 22' provided with a spiral ribbon conveyor 24' driven by a motor 26 acts to propel the metal waste and agitate it within the second portion of the wash bath moving it up along the inclined wall of tank 22 out of the wash bath to be finally discharged through outlet 30 of the second washer section. The lower end of the tank 22' also provides a wier over which the spent detergent solution flows into a trough 28' to be led to the rehabilitation circuit.

it should be understood that washer 20 may well be constructed so that the detergent solution from tank 252' will be discharged directly into the upper end of the first section tank 22 of washer 2i) and used therein to be finally discharged over the wier of tank 22 into trough 2% rather than being led separately from tank 22 to the rehabilitation circuit. Also, although the washer sections are illustrated as being similar in length, in some cases it may be desirable to have the sections of different lengths for best cleaning action on the waste in the screw washer.

Reference may now be made to the sectional showing of HG. 2 which illustrates the cross section of each of the sections of the metal waste washer 20.'From FIG. 2, it will be seen that the generally U-shaped tank 22 is preferably intended to be enclosed along its length by suitable heating means to insure retention of the detergent solution at the desired temperature level for most effective cleaning of the metal waste. In the embodiment illustrated, the exterior of tank 22 has a casing 32 spaced from the exterior of tank 22. This casing is provided with suitable insulation 34 and an inlet 36 and an outlet 38 for flow of steam through the casing 32 so that heating of the washer 2% may be carried out. As a preferred embodiment, the space between casing 32 and tank 22 may contain a plate type internal tube heat exchanger, the tube being connected with inlet 36 and outlet 3%.

When the cleaned metal waste is propelled by spiral ribbon conveyor 24 upwardly within the second section of the metal waste washer 20, it is discharged through outlet 30' from the washer into the surge hopper 4W of a feeder 42. The feeder 42 may be a conventional screw feeder similar to feeder wherein a feed screw 44 driven by motor 46 withdraws cleaned metal waste from surge hopper 4M) and feeds it through outlet to a spinner extractor 5i).

A quantity of cleaned metal waste is discharged from feeder 42 into the bowl of extractor 50. As characteristic of such devices, the bowl is rotated at a high speed whereupon the centrifugal forces exerted upon the cleaned metal waste tend to throw off a substantial quantity of the moisture remaining on the cleaned waste after its exposure to the washing action in washer 2ft. This separated moisture is detergent solution which is conducted away from extractor 50 through line 52 and led to the rehabilitation circuit for the detergent solution as will be described in more detail hereinafter.

The now substantially dried metal waste in clean form is discharged from extractor 50 into a screw feeder 54 which. transports the cleaned waste by rotation of the motor driven screw of such feeder to the intake of a drier ea. In the drier, the already partially dried and cleaned waste coming from the extractor 5b is subjected to drying conditions to drive off further of the remaining moisture contained within the cleaned waste.

As used herein, it will be understood that moisture contemplates primarily the detergent solution which is separated from the cleaned waste first in the extractor El) and subsequently in the drier 56. However, it is to be recognized that this moisture in both cases would contemplate separation of remaining oil that may be a part of the detergent solution entrapped within the metal waste in the detergent solution as the metal waste is discharged from outlet 30' of washer Whereas feeder 42 provided with surge hopper 40 is advantageous where a batch type extractor 50 is employed, it should be understood that the feeder and surge hopper may be omitted where the extractor 50 is one of the so called continuous discharge type extractors. However, such a continuous discharge extractor may not always be justified from a cost and operational standpoint and thus, a batch type extractor where the cake of cleaned waste is removed from the extractor bowl at intervals and passed to feeder 54 may be most economically practical. In such event, when the extractor 50 is shut down and the bowl of the extractor is being cleaned, the feeder 42 will be inoperative and the cleaned waste coming from outlet 30' of the washer 20 can conveniently build up in surge hopper 40.

Also, although the combination of extractor S0 and dryer 56 in series is shown in the illustrated embodiment, with certain types of metal waste and with certain contemplated further uses for the clean dry metal end product, the provision of the dryer 56 may not be necessary. Of course, the saving in the initial cost of the dryer and the saving in the energy required for its operation would be beneficial if sufficiently dry metal product can be obtained by solely using the extractor 50. Likewise, it will be recognized that moisture removal may be achieved solely by use of a dryer 56 without use of an extractor such as 50.

The clean dry metal product leaving the dryer 56, or if the dryer be omitted, leaving the extractor 50, is in a condition of low moisture and low oil content with the sludge or other impurities that originally existed in the metal waste before cleaning removed therefrom. This product is in condition to be fed to a metal melting furnace or to be briquetted for use in othermetalu'rgical processes.

The rehabilitation circuit to restore the detergent solution to its cleaning capability will now be described.

The detergent solution which has ueen used in cleaning the metal waste in washer 2t) overflows into troughs 28 and 28 of the two sections of the washer and is led away from such troughs through line till. This solution, of course, carries with it the oil that has been dissolved from the surfaces of the particles of the metal waste to gether with sludge or other impurities which may have been present in the metal waste prior to its being cleaned. v

The contaminated detergent solution is normally discharged from line 60 unto a coarse screen 62. Of course, the liquid and smaller particles consisting of the detergentsolution, oil and sludge will pass through the screen 62 and be accumulated in surge tank 6d. the coarse screen 62 is only needed where the type of the metal waste being cleaned and consequently the flow of liquid from the washer 20 into line 6% is such that coarse or other undesirably large particles flow along with the liquid. Removal of such coarse or undesirably large particles before further rehabilitation of the detergent solution is desirable in connection with obtaining good action in the application of the centrifugal force used in rehabilitating the detergent solution. Where such coarse or large particles are not present in the flow through line 60 from washer 20, then the coarse screen 62 may be omitted and the liquid from line 60 sent directly to surge tank 4%.

To maintain the detergent solution carrying oil and sludge in suspension, the surge tank 24 may be provided with means to agitate the liquid therein. Such agitation may be obtained by a propeller immersed in the liquid detergent driven through shaft 66 by a suitable motor means (not shown).

The detergent solution carrying sludge and oil is conducted from surge tank 64 through line 68 to a centrifuge 70. The control of flow to the centrifuge 70 through line 68 is obtained by manipulation of valve 72 in line 68. Also it will be noted that a by-pass line 74 containing a control valve 76 is provided communicating with line 60 so that liquid flow therethrough may be directed either to surge tank 64 or through line 74 when valve 76 is open to feed the liquid material directly through line 68 to centrifuge 70.

The operation of centrifuge 70 is conventional in that high rotative speed imparted to the liquid material fed to the centrifuge imparts centrifugal forces to such material such that the liquid portion is separated from the solids and sludge. The solids and sludge are then removed through line 78 from the centrifuge while the remaining solution, constituted by detergent and oil, is drawn from the centrifuge through line 80 by means of pump 82.

The centrifuge 70 may be of the type wherein continuous discharge of the solids and sludge is carried out during centrifuge operation. However, the economics of initial cost and reliability of operation may make the use of a more conventional batch type centrifuge advisable. In a batch type centrifuge, a cake of the solids and sludge is accumulated during operation of the centrifuge and the centrifuge must be stopped and cleaned at intervals varying in time depending upon the rate of accumuiation of the solids and sludge in the centrifuge bowl. Where the batch type centrifuge is used, the feed to the centrifuge through line 68 will, of course, be terminated by closing valve 72 when the centrifuge is being cleaned and at such time, the surge tank 64 will serve to accumulate the contaminated detergent solution leaving washer 2t and flowing through line 60.

The pump 82 draws the liquid portion through line 80 and feeds it to a settling basin 84. Preferably, the settling basin. 84 is associated with the surge tank 64 such that overflow from the basin through trough 86 may be returned to the surge tank 64. The importance of this relationship arises where a batch type centrifuge 70 is employed in the system. When the liquid is withdrawn from surge tank 64 to centrifuge 70, the level in tank 64 will be lowered while the level in settling basin 84 may increase to overflow through trough 86 to maintain a minimum supply in tank 64. However, when the centrifuge 70 is shut down for cleaning, the liquid from line 60 will tend to accumulate in surge tank 64 and restored clean detergent solution will continuously be drawn from settling basin 84 requiring adequate volume in such basin.

The liquid portion consisting of detergent solution and oil both with the sludge removed enters basin 84 through line 80. The oil tends to rise to the surface in this basin with the detergent solution tending to settle beneath the upper strata.

Line 88 is connected to withdraw liquid from basin 24 adjacent the normal surface level of the liquid in such basin. This upper strata will be mostly oil although a portion of the detergent solution will be present. The liquid flowing in line 88 is led to a centrifuge 90. This centrifuge operates to apply centrifugal force to the liquid entering from line 88 to separate the oil from the detergent solution. The separated oil is drawn from centrifuge 90 through line 92, whereas the detergent solution leaves the centrifuge 90 through line 94 and is pumped back to settling basin 84 by pump 96.

The operation of centrifuge 90 and pump 96 may be carried out on a timed period. Since only a portion of the overall detergent washing solution is passed through centrifuge 90 and this portion is drawn from the more concentrated oil layer within setting basin 84, most effective separation of the oil can be achieved by the operation of centrifuge 90.

The restored and clean detergent solution is present in basin 84. Concentrated make up detergent solution will be added to basin 84 through line 98. The restored detergent solution, having its desired cleaning capabilities, is withdrawn from basin 84 through line 100 by the action of pump 102 disposed in such line. This clean detergent solution of proper concentration for the desired cleaning effectiveness enters a heat exchanger 104 wherein the temperature of the detergent solution is raised to the desired level to effect best cleaning of the waste material. Heat exchanger 104 may take a conventional form with the detergent solution entering the bottom of the heat exchanger chamber and the desired hot solution withdrawn from the top through line 106. The heat exchanger casing may appropriately contain a steam coil 108 through which steam is passed to achieve the rise in temperature of the detergent solution.

From line 106, the hot detergent solution is discharged into the upper ends of the sections of washer 20 in the two section washer embodiment illustrated on FIG. 1. This solution flows downwardly in a direction opposite to the movement of the waste material caused by the spiral ribbon conveyors 24 and 24. Thus, most effective counterflow cleaning exposure of the surfaces of metal particles in the waste material to the hot detergent solution is achieved. As note" hereinabove, the temperature of the washer 20 is itself maintained by the heating jacket encasing it so that the detergent solution is maintained at the desired temperature for cleaning.

Although two separate centrifuges 70 and 90, one for sludge removal and the other for oil removal, have been illustrated in the preferred embodiment, it is to be understood that a single centrifuge type separator may be employed to receive the contaminated detergent solution and separate, in a single operation, the sludge and oil as two constituents then passing on the cleaned detergent solution. It is even possible that such a centrifuge type separator wherein centrifugal forces are applied to the contaminated detergent solution to separate sludge and oil as two constituents apart from the detergent solution could have continuous removal of sludge wherein it is not necessary to shut the centrifuge down to clean the bowl of accumulated sludge.

As a further alternative, rather than utilize a centrifuge 70 of the type wherein intermittent cleaning of the bowl is necessary, duplicate solids removing centrifuges could be used in parallel wherein the contaminated detergent solution would be supplied to one centrifuge while it was in operation while the other centrifuge was being cleaned and vice versa. However, it generally would be more economical to provide the simple surge tank 64 rather than involve the added expense of providing'and maintaining two separate solids removing centrifuges.

Also, the oil centrifuge 90 can be sufficiently large to take the full flow from the solids removing centrifuge 70. In such alternative, centrifuge 90 would be disposed to receive the liquid flowing in line 80. However, the use of a smaller centrifuge handling partial flow from and to the basin 84 is preferred. if desired, a floatlevel control for pump 96, sensitive to the level of liquid in basin 84, may be provided to start and stop operation of pump 96. This level control could respond within limits to the contemplated depth of the upper oil strata in basin 84. Thus, in most cases, the liquid going to the oil separator 90 would be largely oil and also only a small part of the flow which is handled through the sludge removing centrifuge 70.

it is to be understood that the form of this invention herein shown and described is to be taken as a preferred example of the invention and various changes and modifications in the arrangement of parts and the interconnection of components may be resorted to without departing from the spirit of the invention or the scope of the appended claims. All such variations and modifications which come within the spirit and scope of the appended claims are intended to be included herein as fully and as completely as if they had been specifically illustrated, described and claimed. Thus, the modification specifically disclosed is exempliary only and not intended to be limiting on the scope of the invention. The scope of the invention is defined by the following claims.

What is claimed is:

l. A process for cleaning oil laden metal waste such as turnings and chips to recover the metal and reclaim the oil carried by said waste comprising the steps of:

providing a flow of a detergent solution in a first direction to form a wash bath for cleaning said metal waste by submersion in said detergent solution and dissolve the oil carried by said waste;

propelling said metal waste through the flow of detergent solution in a direction generally opposite to the direction of flow of said solution to provide counterfiow of waste and solution, the propelling of said waste through said bath serving to agitate said waste and thereby give maximum exposure of the surfaces of the metal waste particles to cleaning by said solution;

removing the cleaned metal waste from said wash bath; separating a substantial quantity of the remaining moisture from said cleaned metal waste;

removing the detergent solution from the bath after its exposure to the metal waste and passing the detergent solution, carrying sludge and oil therewith, through a rehabilitation circuit to restore the solu-- tion cleaning capability before returning the solution to said wash bath for reuse;

subjecting said detergent solution in said rehabilitation circuit to centrifugal force to separate sludge and oil acquired by said solution in cleaning said metal waste;

individually removing said sludge and said oil from the detergent solution as each is centrifugally separated from said solution to restore the solution; adding concentrated make-up detergent solution to the restored solution; heating the make-up and restored detergent solution to the desired cleaning temperature; and returning the heated make-up and restored detergent solution from said rehabilitation circuit to the wash bath.

2. A process for cleaning oil laden metal waste as recited in claim 1 wherein the substantial quantity of remaining moisture is separated from the removed cleaned metal waste by subjecting the cleaned metal waste to centrifugal force, and the separated remaining moisture is returned to said rehabilitation circuit for reuse in the wash bath.

3. A process for cleaning oil laden metal waste as recited in claim It wherein the substantial quantity of remaining moisture is separated from the removed cleaned metal waste by subjecting the cleaned metal 'waste to drying conditions.

i. A process for cleaning oil laden metal waste as recited in claim 1 wherein the removed detergent solution is subjected in said rehabilitation circuit to centrifugal force to separate said sludge from the detergent solution and oil, and the detergent solution and oil subjected to centrifugal force to separate the oil from the detergent solution.

5. A process for cleaning oil laden metal waste as recited in claim 1 wherein said metal waste is propelled upwardly along an incline to move from total immersion in said wash bath out of said wash bath.

6. A process for cleaning oil laden metal waste as recited in claim 5 wherein said provided flow of detergent solution to form a wash bath has a plurality of portions through which said metal waste is propelled with adjacent of said portions being separated by an intermediate portion through which said metal waste is propelled, said metal waste being out of said detergent solution when propelled through said intermediate portion.

"I. A process for cleaning oil laden metal waste as recited in claim 1 wherein the detergent solution removed from the wash bath is screened to remove coarse particles prior to being subjected to centrifugal force.

8. A process for cleaning oil laden metal waste as recited in claim 1 wherein said wash bath is heated to maintain the desired cleaning temperature during agitated counterflow of the waste and solution.

9. A process for cleaning oil laden metal waste as recited in claim 1 wherein the detergent solution removed from the wash bath is accumulated in the rehabilitation circuit in a surge tank; and portions withdrawn from said accumulation and subjected to centrifugal force to separate said sludge therefrom prior to centrifugal separation of said oil from said detergent solution.

iii. A process for cleaning oil laden metal waste as recited in claim 9 wherein the detergent solution and oil are thereafter accumulated in a settling basin; and excess liquid accumulating in said settling basin overflows back to said surge tank.

11. A process for cleaning oil laden metal waste as recited in claim 9 wherein the accumulation of detergent solution in said surge tank is subjected to agitation to maintain the sludge in suspension.

YF l 

2. A process for cleaning oil laden metal waste as recited in claim 1 wherein the substantial quantity of remaining moisture is separated from the removed cleaned metal waste by subjecting the cleaned metal waste to centrifugal force, and the separated remaining moisture is returned to said rehabilitation circuit for reuse in the wash bath.
 3. A process for cleaning oil laden metal waste as recited in claim 1 wherein the substantial quantity of remaining moisture is separated from the removed cleaned metal waste by subjecting the cleaned metal waste to drying conditions.
 4. A process for cleaning oil laden metal waste as recited in claim 1 wherein the removed detergent solution is subjected in said rehabilitation circuit to centrifugal force to separate said sludge from the detergent solution and oil, and the detergent solution and oil subjected to centrifugal force to separate the oil from the detergent solution.
 5. A process for cleaning oil laden metal waste as recited in claim 1 wherein said metal waste is propelled upwardly along an incline to move from total immersion in said wash bath out of said wash bath.
 6. A process for cleaning oil laden metal waste as recited in claim 5 wherein said provided flow of detergent solution to form a wash bath has a plurality of portions through which said metal waste is propelled with adjacent of said portions being separated by an intermediate portion through which said metal waste is propelled, said metal waste being out of said detergent solution when propelled through said intermediate portion.
 7. A process for cleaning oil laden metal waste as recited in claim 1 wherein the detergent solution removed from the wash bath is screened to remove coarse particles prior to being subjected to centrifugal force.
 8. A process for cleaning oil laden metal waste as recited in claim 1 wherein said wash bath is heated to maintain the desired cleaning temperature during agitated counterflow of the waste and solution.
 9. A process for cleaning oil laden metal waste as recited in claim 1 wherein the detergent solution removed from the wash bath is accumulated in the rehabilitation circuit in a surge tank; and portions withdrawn from said accumulation and subjected to centrifugal force to separate said sludge therefrom prior to centrifugal separation of said oil from said detergent solution.
 10. A process for cleaning oil laden metal waste as recited in claim 9 wherein the detergent solution and oil are thereafter accumulated in a settling basin; and excess liquid accumulating in said settling basin overflows back to said surge tank.
 11. A process for cleaning oil laden metal waste as recited in claim 9 wherein the accumulation of detergent solution in said surge tank is subjected to agitation to maintain the sludge in suspension. 